JP3093844B2 - Multi-layer coated granular agricultural material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to agricultural materials such as fertilizers and pesticides, and more particularly to a slow-release granular agricultural material coated with a multilayer film of a specific polymer latex capable of controlling the dissolution rate of an active ingredient. is there.

[0002]

2. Description of the Related Art By coating a water-soluble agricultural material with immediate effect with a water-resistant coating, the dissolution into soil is controlled, and the coated granular agricultural material having a long-lasting effect is used for a long time. Its use is expanding because the effects can be sustained. As a coating agent, a synthetic resin dissolved in sulfur or an organic solvent has been mainly used, but in the case of sulfur, there is a problem that sulfur accumulates in the soil and promotes acidification in the soil. The system can create fire hazards and environmental pollution problems during the coating process. Therefore, it has been proposed to coat agricultural materials with a polymer latex composed of fine synthetic resin particles dispersed in water. In order to sufficiently control the dissolution of agricultural materials with a polymer latex-based coating, the fine synthetic resin particles in the latex must fuse together on the agricultural material surface in the coating process to form a uniform, highly water-resistant continuous film. is necessary. However, there is a problem that the coated granular agricultural materials easily adhere to each other during the coating heating step in which the latex particles are fused together, and this solution is necessary. On the other hand, crops are generally around room temperature (about 1
(5 to 35 ° C), it grows with an increase in temperature and requires a large amount of nutrients. Therefore, in the case of agricultural materials, especially fertilizers, the elution needs to be faster in proportion to the temperature. The elution rate does not significantly deviate from the original elution rate at an intermediate temperature between daytime and nighttime due to repeated nighttime temperature changes (repeated temperature changes do not significantly change the elution control performance of the coating), and the efficiency is systematically planned. It is necessary to form a film that can supply nutrients well. In order to solve these problems, various polymer latex-based coating materials have been studied.

For example, in Japanese Patent Publication No. 37-15832, an appropriate amount of a mineral pigment is added to a vinyl acetate emulsion polymerization solution.
Method of spraying and drying on the surface of fertilizer, Japanese Patent Publication No. 60-186
In the publication No. 40, in a first stage, a thermoplastic emulsion (such as an ethylene-vinyl acetate copolymer emulsion or a polyvinylidene chloride emulsion) or an organic solution is used to prepare a 0.1-0.1
A method in which a water-resistant coating is formed at a coverage of 2%, and a fertilizer is resin-coated at a required coverage with an aqueous emulsion of a thermoplastic resin as a second step. Double-coating type continuous fertilizer having a primary coating consisting of an acid salt or a silicate ester and a secondary coating consisting of a polymer latex;
In the publication, a slow-release coated fertilizer coated with a resin film of an aqueous emulsion having a glass transition temperature of 60 ° C. or higher,
Further, JP-A-64-3094 discloses a slow-release coating obtained by coating a solid fertilizer with a coating material mainly composed of an aqueous emulsion of a thermoplastic resin and a melamine resin, and then heat-treating it at a temperature of 70 ° C. or more. Fertilizers are listed.

[0004]

However, in Japanese Patent Publication No. 37-15832, the water resistance of the coating film is insufficient, so that the elution of fertilizer is not sufficiently controlled. Increasing the amount of coating until a high degree of fertilizer elution control is obtained (about 3% or more) results in the dissolution of the fertilizer, making it impossible to coat the surface of the fertilizer particles with the water-resistant resin. Further, in JP-A-63-112484, it is not possible to cope with a change in the elution control performance due to a repeated temperature change, especially with a secondary coating composed of a mere polymer latex. Further, in JP-A-64-3093, a resin emulsion having a glass transition temperature of 60 ° C. or more is used, so that a continuous film is hardly formed, and not only the elution of fertilizer cannot be sufficiently controlled, but also the film is not sufficiently controlled. It is brittle and has a problem that it is easily broken by impact or the like. Furthermore, Japanese Patent Application Laid-Open No. 64-3094 is not preferable because formaldehyde is released during the coating process and from the product (coated fertilizer).

[0005] There are still many problems to be solved with the granular agricultural material coated with the polymer latex film. The present invention has excellent slow-release properties and the elution control performance is not changed even by repeated temperature changes,
An object of the present invention is to provide a granular agricultural material coated with a polymer latex film whose elution rate faithfully increases in response to an increase in temperature.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies with the aim of obtaining coated granular agricultural materials having the above-mentioned excellent slow-acting properties and resistance to temperature change. As a result, it has been found that when a polymer latex having a different specific glass transition temperature is used as a coating agent, a coated granular agricultural material exhibiting target performance can be obtained, and based on this finding, the present invention has been completed. .

That is, the present invention relates to a multilayer coated granular agricultural material coated with a polymer latex, which comprises (1) a polymer latex having a glass transition temperature of 15 ° C. or less and 100 parts by weight of the granular agricultural material. A coating layer having a coating amount of 2 parts by weight or more, and (2) a coating containing a polymer latex having a glass transition temperature of 30 ° C. or more and having a coating amount of 2 parts by weight or more based on 100 parts by weight of the granular agricultural material. And a multi-layer coated granular agricultural material characterized by containing a layer.

Hereinafter, the present invention will be described in detail. The polymer latex constituting the coating layer in the present invention is obtained by emulsion-polymerizing one or more emulsion-polymerizable monomers in the presence of a polymerization initiator, an emulsifier, or the like by a known method. Examples of the monomer used include (1) methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate,
Esters of unsaturated carboxylic acids such as glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, diethylene glycol diacrylate, and trimethylolpropane triacrylate;
(2) aromatic vinyl compounds such as styrene, vinyltoluene and divinylbenzene; (3) unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid; (4) acrylonitrile and methacrylonitrile (5) aliphatic dienes such as butadiene and isoprene, (6) halogen-substituted vinyl compounds such as vinyl chloride, (7) carboxylic acid vinyl esters such as vinyl acetate, and (8) acrylamide, N-methylol Examples thereof include vinylamide compounds such as acrylamide and N-butoxymethylacrylamide.

Further, natural rubber latex, urethane latex, polyethylene emulsion, etc. obtained by a method other than emulsion polymerization can be used. Examples of the polymerization initiator used in emulsion polymerization include redox initiators such as persulfate, persulfate-sodium thiosulfate, and hydrogen peroxide-oxycarboxylic acid.

Further, as the emulsifier, anionic emulsifiers such as ordinary alkyl diphenyl ether disulfonates, higher alcohol sulfates and alkyl allyl sulfonates, and nonionics such as polyoxyethylene alkyl ethers and polyoxyethylene alkyl esters can be used. System emulsifier and the like. Further, a chain transfer agent such as mercaptans or α-methylstyrene dimer, a chelating agent, a seed latex, a neutralizing agent such as caustic soda or ammonia water, and a salt such as a phosphate or a carboxylate are also optionally used. Can be selected and used.

Further, the polymer latex may contain other various additives. Examples of these additives include a dispersant, a bactericide, a viscosity modifier, an antioxidant, a water-proofing agent and other salts, and the like, if necessary, before polymerization, during polymerization or after polymerization. It may be added. In the present invention, the coating film is composed of a polymer latex having a glass transition temperature of 15 ° C. or less at a coating amount of 2 parts by weight or more (about 5 μm or more in average film thickness) based on 100 parts by weight of the granular agricultural material. Coating layer and granular agricultural material 10
A coating amount of 2 parts by weight or more (average film thickness of about 5 μm or more) with respect to 0 parts by weight, including at least two layers of a coating layer mainly composed of a polymer latex having a glass transition temperature of 30 ° C. or more. It is necessary. It is not preferable to use only a polymer latex coating having a glass transition temperature of 15 ° C. or less, since the dissolution of agricultural materials is fast (dissolution control performance is low). Also,
Only with a polymer latex coating having a glass transition temperature of 30 ° C. or more, the elution of agricultural materials is slow, and although it is preferable, the elution rate due to repeated changes in environmental temperature (15 ° C. and 35 ° C. repeated at regular intervals) is the temperature. Intermediate temperature of difference (25
° C), and the elution rate does not increase in proportion to a mere increase in the environmental temperature, which makes it difficult to supply nutrients to the crop in a planned and efficient manner, which is not preferable.

When a latex polymer having a glass transition temperature in the range of 15 to 30 ° C. is used, the elution rate due to repeated changes in environmental temperature is larger than the elution rate at an intermediate temperature of the temperature difference. It is not preferable because there is no significant difference from the elution rate at high temperature. For the polymer latex having a low glass transition temperature used in the present invention, it is necessary to use those having a glass transition temperature of 15 ° C. or lower, but if the temperature is too low, the coated particles will easily adhere to each other in the coating heating step.
It is preferable to use one having a glass transition temperature of about -10 ° C or higher. In addition, adhesion between coated particles, which tends to occur due to the low glass transition temperature of the polymer, is significantly reduced by using a polymer having a gel content of 70%, preferably 80% or more. Further, the amount is reduced by the combined use of non-film-forming components such as hard latex such as polystyrene latex and inorganic fillers such as talc, calcium carbonate and clay.

In the present invention, it is necessary to use a polymer latex having a high glass transition temperature having a glass transition temperature of 30 ° C. or more. However, if the glass transition temperature is too high, it becomes difficult to form a continuous film. Or less, preferably about 50 ° C. or less. When the above-mentioned non-film-forming components are used in combination, the use amount thereof is preferably about 50% by weight or less.

The glass transition temperature of the polymer latex used for the coating can be arbitrarily set by appropriately combining monomers that give the known glass transition temperature of the homopolymer. The coating amount of each polymer latex coating having a different glass transition point needs to be 2 parts by weight or more per 100 parts by weight of the granular agricultural material, but if it is less than 2 parts by weight, the dissolution control performance is low, and the repetition temperature is low. The elution control performance tends to change due to the change, and the object of the present invention cannot be achieved. Although the elution control performance is improved by increasing the coating amount of each polymer latex film having a different glass transition point, the productivity decreases and the cost increases.
A coating amount of about 0 parts by weight or less is preferable.

The polymer latex having a different glass transition temperature according to the present invention may contain, in addition to the above-mentioned inorganic filler and non-film-forming hard latex, a water-soluble polymer such as starch, sodium alginate, carboxymethylcellulose and polyvinyl alcohol, if necessary. Molecules, salts such as calcium chloride and sodium chloride, silica sols, and crosslinking agents such as epoxy compounds and aziridine compounds may be added.

It is also possible to add a film-forming aid, a plasticizer, or a small amount of an organic solvent for the purpose of improving the film-forming property or drying property of the polymer latex. Glycol n-butyl ether, dipropylene glycol methyl ether acetate, diethylene glycol n-butyl ether, propylene glycol n-butyl ether, ethylene glycol phenyl ether, propylene glycol phenyl ether, ethylene glycol mono-2-ethylhexyl ether, propylene glycol diacetate, dibutyl phthalate , Dioctyl phthalate, dioctyl sebacate, benzyl alcohol, toluene, acetone, methanol, ethanol, n-propanol, isopropanol, butanol, n Hexane, and cyclohexane.

The method for coating the coated granular agricultural material of the present invention is not particularly limited, but may be a heated spray flow (usually 40 to 130 ° C.).
And / or a method of spraying the coating composition continuously or intermittently on the granular agricultural material during or on a rotating pan. A method of forming a multilayer coating is generally obtained by first coating one kind of coating material in one step, and then coating it in one or two or more coating materials in multiple steps.

The granular agricultural material in the present invention is a particulate fertilizer or a water-soluble pesticide, and has a spherical or cylindrical particle shape with a particle size of about 0.5 to 10 mm. There is no particular limitation on the type of fertilizer, for example, advanced chemical fertilizer,
Chemical fertilizers, urea, ammonium sulfate, potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, ammonium phosphate, potassium phosphate, ammonium nitrate and the like. Types of water-soluble pesticides include herbicides, insecticides, fungicides, plant regulators, acaricides, repellents, attractants and the like. The granular agricultural material used in the present invention may be a single particle of these fertilizers and water-soluble pesticides, or particles of a mixture of two or more. If necessary, talc, white carbon, clay,
It may be added with lignin sulfonic acid or the like.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. Parts and% in the examples mean parts by weight and% by weight, respectively.

[0020]

Examples 1 to 6 75 parts by weight of ion-exchanged water and 0.2 parts by weight of an emulsifier (sodium alkylbenzenesulfonate) were charged into a temperature-controllable pressurized reactor equipped with a stirrer purged with nitrogen. Then, the monomer mixture and the chain transfer agent in parts by weight shown in Table 1 were mixed with 20 parts by weight of ion-exchanged water, 0.17 parts of sodium hydroxide, and 0.1% of potassium persulfate (catalyst).
With 6 parts by weight and an emulsifier (sodium alkylbenzene sulfonate) 0.3 part by weight, it is added over 5 to 10 hours,
Polymerized. Then, an aqueous ammonia solution was added to adjust the pH to 9.
Then, steam was blown in to remove residual monomers, and polymer latexes A to E having a solid content of about 48% were obtained.
Table 1 shows the results of determining the glass transition temperature and the gel content of each of the obtained polymer latexes. The glass transfer temperature (Tg) of the dried solid of latex was determined by DSC.
Heating rate 1 using a device (manufactured by Seiko Electronic Industry Co., Ltd.)
The gel content was determined by measuring at 0 ° C./min.
5 g was added, and the mixture was stirred for about 4 hours with a shaker.
The mixture was filtered through a wire mesh of 0 mesh or more, the residue on the wire mesh was dried and weighed, and the result was shown as a weight ratio (%) to the original latex solid.

A polymer latex having a different glass transition temperature and a polystyrene-based latex (a component for preventing adhesion of coated fertilizers in a coating process: L8801 manufactured by Asahi Kasei Kogyo Co., Ltd., particle diameter: about 5000 mm) are used. 100 parts by weight of advanced granulated fertilizer (Asahi Kasei Kogyo Co., Ltd.) under the following conditions using a jet-type coating apparatus shown in FIG.
(Average particle size: about 4 mm) in two parts (secondary) at the ratio of parts by weight shown in Table 2 and dried to prepare a coated granular fertilizer.

Advanced granulated fertilizer: 4 kg Latex concentration (solid content of compound): 10% by weight Spray time (minutes): about 230 minutes Hot air temperature: 90-140 ° C. Coating amount (parts): Latex based on 100 parts by weight of granular fertilizer Solid content by weight The fertilizer dissolution rate of the obtained coated fertilizer was 15 ° C., 25 ° C., 35
Table 2 shows the results of measurement at 150 ° C. and at a temperature change of 15 ° C. and 35 ° C. (repeated every 12 hours). The fertilizer dissolution rate is 1
The ion concentration in water when 0 g of the coated granular fertilizer was immersed in 200 ml of water at each temperature for a certain period of time was determined by measuring the ion concentration in water.

[0023]

Comparative Examples 1 to 6 Polymer latex A obtained in Examples
To D, a polystyrene-based latex (L88 described above)
01) in a formulation as shown in Table 2, and each step was coated with fertilizer in the same manner and under the same conditions as in the Examples,
It dried and produced the coated granular fertilizer (Comparative Examples 1-4). Further, a copolymer latex (A) having a Tg of 1 ° C. and a Tg of 3
The fertilizer was blended with the copolymer (D) at 5 ° C. in a ratio of 2.5 parts: 3.5 parts and L8801 was blended, coated with fertilizer in the same manner and under the same conditions as in the example, and dried. To produce a coated fertilizer (Comparative Example 5). Further, using a copolymer latex (A) having a Tg of 1 ° C. and L8801 blended therein, first, 100 parts of the granular fertilizer is coated with 1 part in the same manner as in the example (primary), and then Tg is increased. 9 parts of a copolymer latex (D) mixed with L8801 at 35 ° C. was coated with 9 parts (secondary) to prepare a two-layer coated fertilizer (Comparative Example 6).
Table 2 shows the results obtained by measuring the dissolution rate of the coated fertilizers obtained in these Comparative Examples 1 to 6 at the same temperatures and repeated temperatures as in the examples.

From the results in Table 2, it can be seen that the granular fertilizer in which the specific latexes having different Tg within the scope of the present invention are multi-layer coated at a coating amount of 2 parts by weight or more has a low dissolution rate and a corresponding increase in dissolution temperature. It can be seen that the dissolution rate also increased, and the dissolution control performance hardly changed with repeated temperature changes.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

According to the present invention, there is provided a slow-acting granular agricultural material coated with a multilayer coating of a polymer latex having specific different glass transition temperatures, and the dissolution control performance can be controlled by repeated temperature changes. It is extremely useful for the agricultural material field because it does not change, faithfully increases the dissolution rate in response to an increase in temperature, and has an excellent slowing effect.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a jet coating apparatus used in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polymer latex introduction pipe 2 Nozzle 3 Granular fertilizer 4 Wire mesh 5 Hot air introduction pipe

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C05G 1/00-5/00 A01N 25/26 A01N 25/34

Claims (1)

(57) [Claims] 1. A multi-layer granular agricultural material coated with a polymer latex, comprising: (1) a polymer latex having a glass transition temperature of 15 ° C. or lower, and a coating amount of 2 parts per 100 parts by weight of the granular agricultural material. A coating layer that is at least part by weight, and (2)
A multilayer coated granular agricultural material comprising: a polymer latex having a glass transition temperature of 30 ° C. or higher; and a coating layer having a coating amount of 2 parts by weight or more based on 100 parts by weight of the granular agricultural material.